Batten, C.J., Woodside Offshore Petroleum Pty. Ltd. (Australia)

Abstract

This paper describes experience with respect to underwater work carried out by Remotely Operated Vehicles (ROV's) on the North West Shelf Development Project, North Rankin 'A' field located 135 km off the North West coast of Australia. The field is operated on behalf of the joint venturers by Woodside Offshore Petroleum Pty Ltd. Installation of the platform and trunkline was completed in 1982 and from this date all underwater work has been carried out by ROV. Typical work includes detailed pipeline and platform inspections, underwater support for the installation of gravity anchors and associated guy wires, general construction, support, underwater cutting, marine fouling removal, scour protection installation and pipeline stabilization.

Information presented in this paper is applicable to all phases of offshore oil and gas production that requires work to be done underwater e.g. exploration drilling, construction, operational inspection and maintenance. The paper describes special tooling procedures and systems developed to perform the above work. Also presented are new information and statistics associated with bulk marine fouling removal by purpose designed/built remotely operated equipment.

The paper concludes that significant underwater work can be performed cost effectively without exposing men to risks associated with the underwater environment and shows that a much larger slice of the underwater work "pie" can be achieved by ROV than has previously been generally accepted.

Specific data related to time/costs associated with performance of significant aspects of the work are presented.

Introduction

This paper describes the experience gained by Woodside Offshore Petroleum Pty Ltd in the application of underwater remote technology on the North West Shelf Development Project, North Rankin

A field. This field is operated north behalf of the North West Shelf Development Project joint venturers by Woodside and is located in a remote area 1000 miles north of Perth and approximately 135 km off the North West Coast of Australia.

The North Rankin 'A' field was the first offshore oil and gas field to be developed in this area. At present the offshore development is comprised of one offshore steel jacket gas production platform (North Rankin A) in 125m water depth and a 1 metre diameter trenched pipeline to shore. Installation of both facilities was completed in 1982. Since that time all underwater inspection, maintenance and repair activities associated with these facilities and underwater construction support for the North Rankin A remedial foundations work has been successfully achieved using remote underwater technology.

This paper includes a brief description of the technology that has been utilised or developed to date followed by a presentation of operational cost data illustrating the cost effectiveness of remote technology when, compared to diving for significant aspects of the work.

EQUIPMENT

Woodside currently owns and contracts the operation and maintenance of three remotely operated vehicles (R.O.V's). These are comprised of one 100 hydraulic HP general purpose work type vehicle (Triton), a smaller inspection and limited work type vehicle (RCV 150) and the recently developed special purpose marine growth removal vehicle (Scimitar). The vehicles and their basic configurations are shown in Figure 1. Each vehicle has it's own Launch and Recovery System (LARS) consisting of an A-frame and winch, a Tether Management System (TMS) for managing cable payout and a surface control module.

The vehicles can be configured with a range of tool packages developed by or for Woodside for specific applications.

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